Spatial navigation is one of the basic abilities that are crucially important for everyday functioning in a complex environment, yet its role in the difficulties experienced by older adults is grossly underestimated. Deficits in spatial navigation are some of the most salient cognitive impairments associated with human aging because of the potential harm to which older adults are exposed, the increased burden placed upon caregivers, and the emotional challenges of decreased autonomy and the need for supervision. Recently, virtual reality (VR) technology has been employed to assess age-related deficits in spatial navigation. The long-term goal of this research is to understand the cognitive and neurobiological processes by which spatial navigation ability declines with age. As a step toward that goal, the proposed research will utilize VR environments to investigate the neural substrates of one component ability of spatial navigation: the computation of path integration by optic flow. The specific goal of this Research Training Proposal is to identify specific factors that contribute to spatial navigational deficits associated with aging. It is expected that these findings will allow for a more complete understanding of the perceptual, cognitive and ultimately the neurological changes that affect this critical aspect of human behavior. [unreadable] [unreadable]